You're doing great.
Yes, I've noticed the aggressive and acidic tone you can take when discussing the details of the abuse; it's simply an expression of your emotional state.
But your T is right that sanitizing your language for your parents is a great idea. You don't want them feeling attacked by your language, only by the facts of your disclosure. Therefore, the language should be as simple as possible.
One suggestion: imagine a situation where things don't go as well as you planned. Talk to your wife about what the two of you might do if it doesn't go well. If, for instance, your parents don't seem to understand, or say the wrong things, etc. -- Just so that you have some sort of visualization and plan for what might happen if things don't go well.
Of course, hopefully things are emotional and then positive. And your father won't think you're less of a man. He will be impressed with how well you handle the disclosure. Hopefully.
As for your "bullshit excuse" to go to the parents without the kids -- it's the holidays; take a present (and a bottle?).
I'll be just fine and dandy
Lord, it's like a hard candy Christmas
I'm barely getting through tomorrow
But I won't let sorrow get me way down.